{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# XPath\n",
    "\n",
    "XPath is short for XML Path Language which is a query language for selecting nodes in an XML document. This is very useful in webscraping because all HTML documents are a form of XML documents."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "import requests\n",
    "from lxml import html"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/html": [
       "<html>\n",
       "  <body>\n",
       "    <h1>Favorite Python Librarires</h1>\n",
       "    <ul>\n",
       "      <li>Numpy</li>\n",
       "      <li>Pandas</li>\n",
       "      <li>requests</li>\n",
       "    </ul>\n",
       "</html>"
      ],
      "text/plain": [
       "<IPython.core.display.HTML object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "%%HTML\n",
    "<html>\n",
    "  <body>\n",
    "    <h1>Favorite Python Librarires</h1>\n",
    "    <ul>\n",
    "      <li>Numpy</li>\n",
    "      <li>Pandas</li>\n",
    "      <li>requests</li>\n",
    "    </ul>\n",
    "  </body>\n",
    "</html>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Load HTML Code\n",
    "Now I'll read the code from cell number 2 and store it in `html_code`. Finally we will parse that into a lxml node object."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<html>\n",
      "  <body>\n",
      "    <h1>Favorite Python Librarires</h1>\n",
      "    <ul>\n",
      "      <li>Numpy</li>\n",
      "      <li>Pandas</li>\n",
      "      <li>requests</li>\n",
      "    </ul>\n",
      "</html>\n"
     ]
    }
   ],
   "source": [
    "html_code = In[2]\n",
    "html_code = html_code[42:-2].replace(\"\\\\n\",\"\\n\")\n",
    "print(html_code)\n",
    "\n",
    "doc = html.fromstring(html_code)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Using xpath to find nodes in a document\n",
    "\n",
    "There many methods for fidning a node that you are interested in from a XML or HTML document. The first way is to write the whole path separated by forward slashes `/`\n",
    "\n",
    "## Reading `<h1>` tag"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<Element h1 at 0x7f447cafa458>"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "title = doc.xpath(\"/html/body/h1\")[0]\n",
    "title"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "To read the text inside that tag you can use the text variable."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Favorite Python Librarires'"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "title.text"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Another way is read the text is to use the `text()` function in xpath."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Favorite Python Librarires'"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "title = doc.xpath(\"/html/body/h1/text()\")[0]\n",
    "title"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Working with multiple items\n",
    "\n",
    "xpath always returns a list. If there are no matches, it will return an empty list. If there is one match it will return a list with one item."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[<Element li at 0x7f447cafa9a8>,\n",
       " <Element li at 0x7f447cafaae8>,\n",
       " <Element li at 0x7f447cafab38>]"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "item_list = doc.xpath(\"/html/body/ul/li\")\n",
    "item_list"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can use `text()` function with multiple items."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['Numpy', 'Pandas', 'requests']"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "doc = html.fromstring(html_code)\n",
    "item_list = doc.xpath(\"/html/body/ul/li/text()\")\n",
    "item_list"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Tag selector without full path\n",
    "\n",
    "you can select any node in your document that matches a node selector without using the full path with a double forward slash `//`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['Numpy', 'Pandas', 'requests']"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "doc = html.fromstring(html_code)\n",
    "item_list = doc.xpath(\"//li/text()\")\n",
    "item_list"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Selecting one result\n",
    "\n",
    "You can select one result from a list using `[index]` after your tag selector. Make sure you use it on the tag selector and not a function selector.\n",
    "\n",
    "**Notice**: This is `index` starts from 1."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['Numpy']"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "doc = html.fromstring(html_code)\n",
    "item_list = doc.xpath(\"/html/body/ul/li[1]/text()\")\n",
    "item_list"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/html": [
       "<html>\n",
       "  <body>\n",
       "    <h1 class=\"text-muted\">Favorite Python Librarires</h1>\n",
       "    <ul class=\"nav nav-pills nav-stacked\">\n",
       "      <li role=\"presentation\"><a href=\"http://www.numpy.org/\">Numpy</a></li>\n",
       "      <li role=\"presentation\"><a href=\"http://pandas.pydata.org/\">Pandas</a></li>\n",
       "      <li role=\"presentation\"><a href=\"http://python-requests.org/\">requests</a></li>\n",
       "    </ul>\n",
       "    <h1 class=\"text-success\">Favorite JS Librarires</h1>\n",
       "    <ul class=\"nav nav-tabs\">\n",
       "      <li role=\"presentation\"><a href=\"http://getbootstrap.com/\">Bootstrap</a></li>\n",
       "      <li role=\"presentation\"><a href=\"https://jquery.com/\">jQuery</a></li>\n",
       "      <li role=\"presentation\"><a href=\"http://d3js.org/\">d3.js</a></li>\n",
       "    </ul>\n",
       "</html>"
      ],
      "text/plain": [
       "<IPython.core.display.HTML object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "%%HTML\n",
    "<html>\n",
    "  <body>\n",
    "    <h1 class=\"text-muted\">Favorite Python Librarires</h1>\n",
    "    <ul class=\"nav nav-pills nav-stacked\">\n",
    "      <li role=\"presentation\"><a href=\"http://www.numpy.org/\">Numpy</a></li>\n",
    "      <li role=\"presentation\"><a href=\"http://pandas.pydata.org/\">Pandas</a></li>\n",
    "      <li role=\"presentation\"><a href=\"http://python-requests.org/\">requests</a></li>\n",
    "    </ul>\n",
    "    <h1 class=\"text-success\">Favorite JS Librarires</h1>\n",
    "    <ul class=\"nav nav-tabs\">\n",
    "      <li role=\"presentation\"><a href=\"http://getbootstrap.com/\">Bootstrap</a></li>\n",
    "      <li role=\"presentation\"><a href=\"https://jquery.com/\">jQuery</a></li>\n",
    "      <li role=\"presentation\"><a href=\"http://d3js.org/\">d3.js</a></li>\n",
    "    </ul>\n",
    "</html>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<html>\n",
      "  <body>\n",
      "    <h1 class=\"text-muted\">Favorite Python Librarires</h1>\n",
      "    <ul class=\"nav nav-pills nav-stacked\">\n",
      "      <li role=\"presentation\"><a href=\"http://www.numpy.org/\">Numpy</a></li>\n",
      "      <li role=\"presentation\"><a href=\"http://pandas.pydata.org/\">Pandas</a></li>\n",
      "      <li role=\"presentation\"><a href=\"http://python-requests.org/\">requests</a></li>\n",
      "    </ul>\n",
      "    <h1 class=\"text-success\">Favorite JS Librarires</h1>\n",
      "    <ul class=\"nav nav-tabs\">\n",
      "      <li role=\"presentation\"><a href=\"http://getbootstrap.com/\">Bootstrap</a></li>\n",
      "      <li role=\"presentation\"><a href=\"https://jquery.com/\">jQuery</a></li>\n",
      "      <li role=\"presentation\"><a href=\"http://d3js.org/\">d3.js</a></li>\n",
      "    </ul>\n",
      "</html>\n"
     ]
    }
   ],
   "source": [
    "html_code = In[11]\n",
    "html_code = html_code[42:-2].replace(\"\\\\n\",\"\\n\")\n",
    "print(html_code)\n",
    "\n",
    "doc = html.fromstring(html_code)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Attributes selector\n",
    "\n",
    "In this example we have two `<h1>` tags with different css classes. We can select tags based on css classes as follows:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Favorite Python Librarires'"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "title = doc.xpath(\"/html/body/h1[@class='text-muted']/text()\")[0]\n",
    "title"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## `contains()` function\n",
    "\n",
    "I want to select all items in the first list. I could use the full class for selection or I could just use one of the classed only used in the first list with the `contains()` function."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['Numpy', 'Pandas', 'requests']"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "item_list = doc.xpath(\"/html/body/ul[contains(@class,'nav-stacked')]/li/a/text()\")\n",
    "item_list"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Returning attributes\n",
    "\n",
    "What if we want to read the `href` attribute of the `<a>` tag to get the link. This is how you do that:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['http://www.numpy.org/',\n",
       " 'http://pandas.pydata.org/',\n",
       " 'http://python-requests.org/']"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "item_list = doc.xpath(\"/html/body/ul[contains(@class,'nav-stacked')]/li/a/@href\")\n",
    "item_list"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Real world example\n",
    "\n",
    "Read the list of languages with 1M+ articles on http://www.wikipedia.org/"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "response = requests.get(\"http://www.wikipedia.org\")\n",
    "doc = html.fromstring(response.content, parser=html.HTMLParser(encoding=\"utf-8\"))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['Deutsch',\n",
       " 'English',\n",
       " 'EspaÃ±ol',\n",
       " 'FranÃ§ais',\n",
       " 'Italiano',\n",
       " 'Nederlands',\n",
       " 'Polski',\n",
       " 'Ð ÑƒÑÑÐºÐ¸Ð¹',\n",
       " 'Sinugboanong Binisaya',\n",
       " 'Svenska',\n",
       " 'Tiáº¿ng Viá»‡t',\n",
       " 'Winaray']"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "lang_list = doc.xpath(\"//div[@class='langlist langlist-large hlist'][1]/ul/li/a/text()\")\n",
    "lang_list"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": []
  }
 ],
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  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.4.3"
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